Therapeutic ultrasound system

ABSTRACT

An ultrasound system has a catheter including an elongate flexible catheter body having at least one lumen extending longitudinally therethrough. The catheter further includes an ultrasound transmission member extending longitudinally through the lumen of the catheter body, the ultrasound transmission member having a proximal end connectable to a separate ultrasound generating device and a distal end coupled to the distal end of the catheter body. The distal end of the catheter body is deflectable. The ultrasound system also includes a sonic connector that connects the ultrasound transmission member to an ultrasound transducer. The ultrasound system also provides a method for reverse irrigation and removal of particles.

RELATED CASES

This is a division of Ser. No. 10/211,418, filed Aug. 2, 2002, now U.S.Pat. No. 6,855,123, whose disclosure is incorporated by this referenceas though fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to medical equipment, and moreparticularly, to a therapeutic ultrasound system for ablatingobstructions within tubular anatomical structures such as blood vessels.

2. Description of the Prior Art

A number of ultrasound systems and devices have heretofore been proposedfor use in ablating or removing obstructive material from blood vessels.However, all of these systems and devices generally encounter someproblems which are not always adequately addressed by these systems anddevices.

A first type of problem relates generally to the effective transmissionof ultrasound energy from an ultrasound source to the distal tip of thedevice where the ultrasound energy is applied to ablate or removeobstructive material. Since the ultrasound source, such as a transducer,is usually located outside the human body, it is necessary to deliverthe ultrasound energy over a long distance, such as about 150 cm, alongan ultrasound transmission wire from the source to the distal tip.Attenuation of the acoustical energy along the length of thetransmission wire means that the energy reaching the distal tip isreduced. To ensure that sufficient energy reaches the distal tip, agreater amount of energy must be delivered along the transmission wirefrom the source to the distal tip. This transmission of increased energyalong the transmission wire may increase the fatigue experienced by thetransmission wire at certain critical locations, such as at theconnection between the transducer and the transmission wire.

In addition to the above, it is important to be able to convenientlyconnect and disconnect the ultrasound transmission member from thetransducer without creating unnecessary stresses on the ultrasoundtransmission wire, or weakening the ultrasound transmission wire. Sincethe transducer is a non-sterile unit, and the ultrasound transmissionwire is a sterile unit, a transducer can be used with numerous differentultrasound transmission wires in numerous different procedures.Therefore, there is also a need to provide a removable connectionbetween the ultrasound transmission wire and the transducer that caneffectively transmit ultrasound energy while maintaining the integrityof the ultrasound transmission wire.

A second type of problem relates to the need for accurately positioningthe ultrasound device inside a patient's vasculature, and in particular,where the vasculature contains smaller and more tortuous vessels. Toaddress this need, flexible and low-profile ultrasound devices have beenprovided which allow the device to be navigated through small andtortuous vessels. However, these devices have not been completelysatisfactory in meeting these navigational needs.

A third type of problem relates to the removal of particles that areproduced when the obstructive material is ablated or broken up. It isimportant that these particles be removed from the patient's vascularsystem to avoid distal embolization and other clinical complications.

Thus, there still exists a need for improved ultrasound systems havingultrasound devices or catheters which address the aforementionedproblems.

SUMMARY OF THE DISCLOSURE

The terms “ultrasound transmission wire” and “ultrasound transmissionmember” shall be used interchangeably herein, and are intended to meanthe same element.

It is an object of the present invention to provide an ultrasound devicethat provides an improved connection between the ultrasound transmissionmember and the transducer.

It is another object of the present invention to provide an ultrasounddevice that has a removable connection between the ultrasoundtransmission member and the transducer.

It is yet another object of the present invention to provide anultrasound device with a distal end that can effectively navigatesmaller and more tortuous vessels.

It is yet another object of the present invention to provide anultrasound device that effectively removes particles from the patient'svascular system.

In order to accomplish the objects of the present invention, there isprovided an ultrasound system having a catheter including an elongateflexible catheter body having at least one lumen extendinglongitudinally therethrough. The catheter further includes an ultrasoundtransmission member extending longitudinally through the lumen of thecatheter body, the ultrasound transmission member having a proximal endconnectable to a separate ultrasound generating device and a distal endcoupled to the distal end of the catheter body. In one embodiment, thedistal end of the catheter body is deflectable. The ultrasound system ofthe present invention can incorporate one of several embodiments ofsonic connectors that connect the ultrasound transmission member to anultrasound transducer. The ultrasound system of the present inventionalso provides a method for reverse irrigation and removal of particles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an ultrasound system according to thepresent invention.

FIG. 2 is a cross-sectional view of the distal end of an ultrasoundcatheter that can be used with the system of FIG. 1.

FIG. 3 is a cross-sectional view of the distal end of another ultrasoundcatheter that can be used with the system of FIG. 1.

FIG. 4 is a cross-sectional view of the catheter of FIG. 3 shown withthe distal end deflected.

FIG. 5 is cross-sectional view of one embodiment of a sonic connectorassembly that can be used with the system of FIG. 1.

FIG. 6 is an enlarged cross-sectional view of the sonic connector inFIG. 5.

FIGS. 7-11 are cross-sectional views of different embodiments of sonicconnector assemblies that can be used with the system of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description is of the best presently contemplatedmodes of carrying out the invention. This description is not to be takenin a limiting sense, but is made merely for the purpose of illustratinggeneral principles of embodiments of the invention. The scope of theinvention is best defined by the appended claims. In certain instances,detailed descriptions of well-known devices, compositions, components,mechanisms and methods are omitted so as to not obscure the descriptionof the present invention with unnecessary detail.

FIG. 1 illustrates an ultrasound system according to the presentinvention for use in ablating and removing occlusive material inside thevessel of an animal or human being. The ultrasound system includes anultrasonic catheter device 10 which has an elongate catheter body 12having a proximal end 14, a distal end 16, and defining at least onelumen extending longitudinally therethrough. The ultrasound catheterdevice 10 is operatively coupled, by way of a proximal connectorassembly 20, to an ultrasound transducer 22. The ultrasound transducer22 is connected to a signal generator 24. The signal generator 24 can beprovided with a foot actuated on-off switch 26. When the on-off switch26 is depressed, the signal generator 24 sends an electrical signal tothe ultrasound transducer 22, which converts the electrical signal toultrasound energy. Such ultrasound energy subsequently passes throughthe catheter device 10 is delivered to the distal end 16. A guidewire 28may be utilized in conjunction with the catheter device 10, as will bemore fully described below.

FIG. 2 illustrates one non-limiting configuration for the distal end 16of the catheter body 12 of the catheter device 10. The catheter body 12is formed of a flexible polymeric material such as nylon (Pebax™)manufactured by Atochimie, Cour be Voie, Hauts Ve-Sine, France. Theflexible catheter body 12 is preferably in the form of an elongate tubehaving one or more lumens extending longitudinally therethrough.

Referring now to FIG. 2, the catheter body 12 has a lumen 18. Extendinglongitudinally through the lumen 18 of the catheter body 12 is anelongate ultrasound transmission member 30 having a proximal end whichis removably connectable to the ultrasound transducer 22 such thatultrasound energy will pass through the ultrasound transmission member30. As such, when the foot actuated on-off switch 26 operativelyconnected to the ultrasound transducer 22 is depressed, ultrasoundenergy will pass through the ultrasound transmission member 30 to thedistal end 16 of the catheter body 12. More particularly, the ultrasoundtransmission member 30 serves to transmit the ultrasound energy from theproximal connector assembly 20 to a distal head 34 mounted on the distalend 16 of the catheter body 12.

The distal head 34 has a substantially rigid member affixed to thedistal end 16 of the catheter body 12. In the embodiment shown, thedistal head 34 has a generally rounded configuration, and has a proximalportion 34 b whose outer diameter is slightly less than the outerdiameter of the distal portion 34 a of the distal head 34, so as todefine an annular shoulder 38 to which a distal end 42 of a coil 40 isattached. The proximal end 44 of the coil 40 is attached to the opendistal end 46 of the catheter body 12 such that the proximal portion 34b is not received inside the catheter body 12 but is spaced-aparttherefrom. Preferably, the outer diameter of the coil 40 is about thesame as the outer diameter of the catheter body 12 and the distalportion 34 a, thereby forming a generally smooth outer surface at thejuncture of the distal head 34, the coil 40 and the catheter body 12, asshown in FIG. 2.

The attachment of the coil 40 to the distal head 34 and the catheterbody 12 may be accomplished by any suitable manner. One manner isthrough the use of an adhesive which is applied to the interfacingsurfaces to be attached. The adhesive may comprise any suitableadhesive, such as cyanoacrylate (e.g., Loctite™ Corp., Ontario, Canadaor Aron Alpha™, Borden, Inc., Columbus, Ohio) or polyurethane (e.g.,Dymax™, Dymax Engineering Adhesive, Torrington, Conn.). As analternative to the use of adhesives, various mechanical or frictionalconnections, such as screw threads, lugs, or other surface modificationsformed on one surface, can also be used, with corresponding grooves,detents, or surface modifications formed in the interfacing surface tobe attached.

In addition, a guidewire tube 80 defining a guidewire lumen extendsthrough the lumen 18, the coil 40 and a bore 82 formed through thedistal head 34. The guidewire tube 80 can be bonded or attached at alocation 84 to the bore 82 according to one of the attachment or bondingmethods described above. The guidewire tube 80 can extend along thelength of the catheter body 12 if catheter device 10 is an“over-the-wire” catheter device. If catheter device 10 is a “monorail”catheter device, as shown in FIG. 1, the guidewire tube 80 terminates ata guidewire aperture 86 adjacent but slightly proximal from the distalend 16 of the catheter body 12, at which the guidewire 28 exits thecatheter body 12 (as shown in FIG. 1).

The distal head 34 may be formed of any suitable rigid material, such asmetal or plastic. The distal head 34 is preferably formed of radiodensematerial so as to be easily discernible by radiographic means.Accordingly, the distal head 34 may preferably be formed of metal or,alternatively, may be formed of plastic, ceramic, glass, or rubbermaterials, optionally having one or more radiodense markers affixedthereto or formed therein. For example, the distal head 34 may be moldedof plastic, such as acrylonitrile-butadine-styrene (ABS) and one or moremetallic foil strips or other radiopaque markers may be affixed to suchplastic distal head 34 in order to impart sufficient radiodensity topermit the distal head 34 to be readily located by radiographic means.Additionally, in embodiments wherein the distal head 34 is formed ofmolded plastic or other non-metallic material, a quantity of radiodensefillers, such as powdered Bismuth or Barium Sulfate (BaSO₄) may bedisposed within the plastic or other non-metallic material of which thedistal head 34 is formed so as to impart enhanced radiodensity thereto.

The ultrasound transmission member 30 extends through the lumen 18 andthe coil 40, and is inserted into a bore 62 which extends longitudinallyinto the proximal portion 34 b of the distal head 34. The distal end ofthe ultrasound transmission member 30 is firmly held within the bore 62by the frictional engagement thereof to the surrounding material of thedistal head 34, or by other mechanical or chemical affixation means suchas but not limited to weldments, adhesive, soldering and crimping. Firmaffixation of the ultrasound transmission member 30 to the distal head34 serves to facilitate direct transmission of the quanta of ultrasonicenergy passing through the ultrasound transmission member 30 to thedistal head 34. As a result, the distal head 34, and the distal end 16of the catheter device 10, are caused to undergo ultrasonic vibration inaccordance with the combined quanta of ultrasonic energy beingtransmitted through the ultrasound transmission member 30.

The coil 40 can be a single coil, a braid, a multilead coil, across-wound coil, a rounded wire coil, a flat wire coil, or anycombination thereof. The coil 40 is preferably elastic and is made of amaterial having high elongation so as to conform to the configuration ofthe distal end 16 and to vibrate with the distal head 34 uponapplication of ultrasound-energy. The coil 40 can be embedded inside apolymer jacket or coating, such as but not limited to PTFE,polyurethane, polyamide or nylon. The length of the coil 40 can rangefrom 0.1 to 150 cm. Thus, the coil 40 provides several benefits. First,the coil 40 provides an elastic attachment of the distal head 34 to thecatheter body 12. Second, the coil 40 allows the distal head 34 tofreely vibrate independent of the catheter body 12. Third, the coil 40provides an additional connection between the catheter body 12 and thedistal head 34 since the coil 40 will hold the distal head 34 to thecatheter device 10 in the event that the ultrasound transmission member30 breaks or fractures.

In the preferred embodiment, the ultrasound transmission member 30 maybe formed of any material capable of effectively transmitting theultrasonic energy from the ultrasound transducer 22 to the distal head34, including but not necessarily limited to metal, plastic, hardrubber, ceramic, fiber optics, crystal, polymers, and/or compositesthereof. In accordance with one aspect of the invention, all or aportion of the ultrasound transmission member 30 may be formed of one ormore materials which exhibit super-elasticity. Such materials shouldpreferably exhibit super-elasticity consistently within the range oftemperatures normally encountered by the ultrasound transmission member30 during operation of the catheter device 10. Specifically, all or partof the ultrasound transmission member 30 may be formed of one or moremetal alloys known as “shape memory alloys”.

Examples of super-elastic metal alloys which are usable to form theultrasound transmission member 30 of the present invention are describedin detail in U.S. Pat. No. 4,665,906 (Jervis); U.S. Pat. No. 4,565,589(Harrison); U.S. Pat. No. 4,505,767 (Quin); and U.S. Pat. No. 4,337,090(Harrison). The disclosures of U.S. Pat. Nos. 4,665,906; 4,565,589;4,505,767; and 4,337,090 are expressly incorporated herein by referenceinsofar as they describe the compositions, properties, chemistries, andbehavior of specific metal alloys which are super-elastic within thetemperature range at which the ultrasound transmission member 30 of thepresent invention operates, any and all of which super-elastic metalalloys may be usable to form the super-elastic ultrasound transmissionmember 30.

In particular, the present invention provides an ultrasound transmissionmember 30, all or part of which may be made of a super-elastic metalalloy which exhibits the following physical properties:

PROPERTY UNIT VALUE Nickel Atomic Weight Min. 50.50-Max. 51.50 WeightPercent Min. 55.50-Max. 56.07 Titanium % Remainder Total gas %  0.15 Maxcontent (O, H, N) Carbon Content % 0.010 Max Maximum Tensile PSI 220KStrength Elongation % 10-16 Melting Point Celcius 1300-1350 Densityg/cm³ 6.5

This alloy provides an ultrasound transmission member 30 thatexperiences minimum attenuation of ultrasound energy, and which has theability to be navigated through the complex bends of tortuous vesselswithout experiencing any permanent deformation which would otherwiseresult in transmission losses.

Referring now to FIG. 1, the proximal connector assembly 20 of thecatheter device 10 has a Y-connector 320. The frontal portion of theY-connector 320 is connected to the proximal end 14 of the catheter body12. The proximal end of the rear portion of the proximal connectorassembly 20 is attached to a sonic connector assembly 66 which isconfigured to effect operative and removable attachment of the proximalend of the ultrasound transmission member 30 to the horn of theultrasound transducer 22. The sonic connector assembly or apparatus ispreferably configured and constructed to permit passage of ultrasoundenergy through the ultrasound transmission member 30 with minimallateral side-to-side movement of the ultrasound transmission member 30while, at the same time, permitting unrestricted longitudinalforward/backward vibration or movement of the ultrasound transmissionmember 30. A more detailed description of the sonic connector assembly66, and the operative removable attachment of the ultrasoundtransmission member 30 to the ultrasound transducer 22, are describedbelow.

In the ultrasound system according to the present invention, aninjection pump 68 or IV bag is connected, by way of an infusion tube 70,to an infusion port or sidearm 72 of the Y-connector 320. The injectionpump 68 is used to infuse coolant fluid (e.g., 0.9% NaCl solution) intoand/or through the catheter device 10, and more particularly into thelumen 18 of the catheter body 12. Such flow of coolant fluid may beutilized to prevent overheating of the ultrasound transmission member 30extending longitudinally through the lumen 18. Due to the desirabilityof infusing coolant fluid into the catheter body 12, at least one fluidoutflow channel 74 extends longitudinally through the distal head 34 topermit the coolant fluid to flow from the lumen 18 out of the distal end16 of the catheter body 12. See arrows 94 in FIG. 2. Such flow of thecoolant fluid through the lumen 18 serves to bathe the outer surface ofthe ultrasound transmission member 30, thereby providing for anequilibration of temperature between the coolant fluid and theultrasound transmission member 30. Thus, the temperature and/or flowrate of coolant fluid may be adjusted to provide adequate cooling and/orother temperature control of the ultrasound transmission member 30.

In addition to the foregoing, the injection pump 68 may be utilized toinfuse a radiographic contrast medium into the catheter device 10 forpurposes of imaging. Examples of iodinated radiographic contrast mediawhich may be selectively infused into the catheter device 10 via theinjection pump 68 are commercially available as Angiovist 370 fromBerlex Labs, Wayne, N.J. and Hexabrix from Malinkrodt, St. Louis, Mo.

Although the catheter device 10 in FIG. 1 is illustrated as a “monorail”catheter device, the catheter device 10 can be provided as an“over-the-wire” catheter device without departing from the spirit andscope of the present invention. The structural and operative principlesof “monorail” and “over-the-wire” guidewire techniques are well known tothose skilled in the art, and are not further discussed herein.

The catheter body 12 illustrated in FIG. 2 is deployed with the use of aguidewire as either a “monorail” or an “over-the-wire” catheter device.On the other hand, the catheter body 12 can be deployed without the useof a guidewire, as illustrated in FIG. 3, where catheter body 12 x andits distal end 16 x are essentially the same as catheter body 12 and itsdistal end 16, except that the channel 74, the guidewire tube 80 and thebore 82 are omitted from the distal head 34 x. The coils 40 x andultrasound transmission member 30 x can be the same as the coils 40 andultrasound transmission member 30 in FIG. 2. FIG. 3 further illustratesthe provision of a deflection wire 88 that extends from the distal head34 x through the lumen 18 x and exits the catheter body 12 x via an exitport adjacent the proximal end 14 of the catheter body 12 x (see FIG.1). The deflection wire 88 can be rounded or flat, and can be made froma flexible and strong material such as stainless steel or nylon. Thedeflection wire 88 has a distal end which is secured to the distal head34 x by bonding, welding, fusing and similar mechanisms, and a proximalend that is connected to a stretching knob 90 that is provided at theproximal end of the wire 88. When the knob 90 is pulled, the deflectionwire 88 will stretch, thereby causing the distal end 16 x to deflect, asshown in FIG. 4. When the pulling motion on the knob 90 is released, thewire 88 will relax and return to its normally straight orientation.

It is also possible to provide a deflecting distal end 16 x by shapingthe distal end 16 or 16 x of the catheter body 12 or 12 x. Shaping thedistal end 16 or 16 x at predetermined angles with respect to thecatheter body 12 or 12 x provides the same function as deflecting thedistal end 16 x. According to the present invention, shaping the distalend 16 or 16 x can be accomplished by radiofrequency, steam or otherheat generated methods. It is important that the shaping or pre-shapingof the distal end 16 or 16 x not induce stresses or damage to theultrasound transmission member 30 or 30 x. The shaping of the distal end16 or 16 x can be done prior to the actual medical procedure or can bedone by the manufacturer or the physician using shaping techniques thatare well-known in the art. The shaped catheter body 12 or 12 x can thenbe re-shaped as desired using the same methods.

The present invention further provides a sonic connector assembly 66that effectively connects the ultrasound transmission member 30 to thetransducer 22 in a manner which reduces step sonic amplification andprovides a smooth connection transition of the transmission member 30,thereby reducing the stress and fatigue experienced by the transmissionmember 30. The sonic connector assembly 66 includes a sonic connectorthat functions to grip or otherwise retain the proximal end of theultrasound transmission member 30, and which can be removably connectedto the transducer 22. In other words, the sonic connector serves as anattaching element that couples the ultrasound transmission member 30 tothe transducer 22. The present invention provides several differentembodiments of sonic connectors that can be used with the sonicconnector assembly 66. Each of these sonic connectors functions toremovably connect an ultrasound catheter to a transducer 22 in a mannerwhich minimizes transverse movement at the connection area whilemaintaining longitudinal ultrasound energy propagation. In this regard,longitudinal vibrations are desirable, while transverse vibrations maycause breakage in the ultrasound transmission member 30. Since thegreatest amount of transverse motion occurs at the connection areabetween the ultrasound transmission member 30 and the transducer 22,elimination of transverse movements at the connection area between theultrasound transmission member 30 and the transducer 22 is crucial inprotecting the integrity of the ultrasound transmission member 30 andminimizing the potential for breakage of the ultrasound transmissionmember 30.

In one embodiment illustrated in FIG. 5, the sonic connector assembly 66has a sonic connector 200 housed inside the proximal bore 300 of a knobhousing 302. The sonic connector 200 is enlarged in FIG. 6 for greaterclarity. The proximal bore 300 in the knob housing 302 has a rearsection 301 that has a proximal opening into which a transducer horn(not shown) may be inserted to engage the sonic connector 200. Anenlarged bore 322 is provided at the distal end of the knob housing 302,with the enlarged bore 322 communicating with a channel 310. Thestructure and characteristics of the knob housing and the transducerhorn are well-known in the art, and are not described in greater detailherein. For example, the knob housing and transducer horn can be thesame as those illustrated in U.S. Pat. No. 5,989,208 to Nita, whoseentire disclosure is incorporated by this reference as though set forthfully herein.

The sonic connector 200 has a central portion 210 having a verticalthrough-bore 212 which receives a locking pin 306. The locking pin 306is inserted through an opening 308 in the knob housing 302 and isreceived inside the through-bore 212 to retain the sonic connector 200at a pre-determined position inside the proximal bore 300 of the knobhousing 302, as best illustrated in FIG. 12 of U.S. Pat. No. 5,989,208.The sonic connector 200 further includes a front shaft 218 extendingdistally from the central portion 210. The sonic connector 200 also hasa threaded stem 226 extending proximally from the central portion 210 topermit the distal end of the transducer horn to be threadably screwedonto and removably attached to the sonic connector 200.

The distal end of the front shaft 218 has a bore 220 that terminatesbefore the central portion 210. The proximal end of the ultrasoundtransmission member 30 extends through the channel 310 in the knobhousing 302 and through the bore 220, and is dimensioned to be snuglyfitted inside the bore 220. The proximal end of the ultrasoundtransmission member 30 is secured inside the inner bore 220 by welding,bonding, crimping, soldering, or other conventional attachmentmechanisms. As one non-limiting example, the proximal end of theultrasound transmission member 30 is crimped to the front shaft 218 atlocation A.

An intermediate member 224 is seated in the enlarged bore 322 and has abore that receives (i.e., circumferentially surrounds) the ultrasoundtransmission member 30. In other words, the intermediate member 224 ispositioned between the ultrasound transmission member 30 and theenlarged bore 322. The intermediate member 224 is preferably made of anelastic material, and non-limiting examples include a polymer or rubber.The intermediate member 224 functions to absorb transversemicro-motions, thereby minimizing the undesirable transverse vibrations.

The proximal end of the Y-connector 320 can be threadably engaged to theopening of the enlarged bore 322. Thus, the intermediate member 224 isspaced apart from the crimp location A by a distance of aboutone-quarter wavelength.

FIG. 7 illustrates another embodiment of a sonic connector 200 b that issimilar to the sonic connector 200 in FIG. 5. As a result, the samenumerals are utilized to designate the same elements in both FIGS. 5 and7, except that the same element in FIG. 7 includes a “b” in thedesignation. The sonic connector 200 b has a separate tubular member 234which is spaced-apart from the distal-most end of the front shaft 218 b.The tubular member 234 has a bore that retains an intermediate member224 b, which in turn surrounds a portion of the ultrasound transmissionmember 30. Thus, the intermediate member 224 b is now provided inside atubular member 234 as opposed to being provided in the knob housing 302(as in FIG. 5). The tubular member 234 can be crimped to the ultrasoundtransmission member 30. Thus, there are two connection locations A and Bin FIG. 7. The crimp location A involves a crimp of the front shaft 218b and the ultrasound transmission member 30. The crimp location Binvolves a crimp of the tubular member 234, the intermediate member 224b, and the ultrasound transmission member 30. In this manner, these twoconnection locations actually provide two spaced-apart connectionlocations, with one location (i.e., B) being separate from the actualsonic connector 200 b and acting as a transverse absorber.

The sonic connector is normally attached to the transducer at thehighest displacement point of the transducer, which is at the connectionwith the sonic connector. Studies have shown that one area where theultrasound transmission member 30 experiences a great amount of stressis about one-quarter wavelength from the connection with the sonicconnector. Therefore, the embodiment in FIG. 7 provides a transverseabsorber (i.e., 224 b) that is positioned at a location along theultrasound transmission member 30 that is about one-quarter wavelengthfrom the connection with the sonic connector. The configuration in FIG.7 eliminates a greater amount of transverse energy at the proximal endof the ultrasound transmission member 30, thereby minimizing potentialbreakage of the ultrasound transmission member 30. In addition, reducedtransverse movements propagating towards the distal end of the catheter10 will result in the generation of less heat so that an ultrasoundtransmission member 30 with a smaller cross-sectional area can be used.This will in turn result in a more flexible catheter 10 that allows thecatheter 10 to run a continuous wave mode (since pulsing is one methodof reduce heat). The combined use of a continuous wave mode of operationand pulsing would allow for the ultrasound ablation of a larger varietyof tissues (e.g., soft, hard, fibrous).

The intermediate members 224, 224 b function as absorbers that minimizeundesirable transverse vibrations. To be effective in minimizingtransverse vibrations, the absorber needs to be seated tightly aroundthe ultrasound transmission member 30 so as to impact themicro-transverse motions vibrations or motions experienced by theultrasound transmission member 30. This tight seat, fit or grip isgenerally accomplished by creating an additional force, or squeezing theabsorber against the ultrasound transmission member 30, which can beperformed using one of two methods. In a first method, the absorber issqueezed longitudinally. Unfortunately, this longitudinal force maydeform the absorber and may create a non-uniform grip which might inturn provide an inconsistent grip around the ultrasound transmissionmember 30. Fortunately, this inconsistency can be overcome by providinga plurality of O-rings around the ultrasound transmission member 30, asdescribed below in connection with FIG. 8. A second method uses aperpendicular (i.e., transverse) force to compress the absorber aroundthe ultrasound transmission member 30, and the crimping techniquesdescribed in FIGS. 5 and 7 herein are examples of this second method.

FIG. 8 illustrates how the sonic connector 200 shown in FIG. 6 can beused with a slightly different knob housing to overcome the inconsistentgrip around the ultrasound transmission member 30 provided by alongitudinal gripping force. The knob housing 302 c in FIG. 8 is similarto the knob housing 302 in FIG. 5, so the same numerals are utilized todesignate the same elements in both FIGS. 5 and 8, except that the sameelement in FIG. 8 includes a “c” in the designation. In the knob housing302 c, the bore 300 c is provided as a single bore, without the channel310 and the enlarged bore 322. The ultrasound transmission member 30extends through the Y-connector 320 and into the bore 300 c, and aplurality of O-rings 330 are provided around the ultrasound transmissionmember 30 inside the bore 300 c. Thus, the O-rings 330 function like theabsorbers 224 and 224 b, and are seated tightly around the ultrasoundtransmission member 30 adjacent the connection area of the ultrasoundtransmission member 30 and the transducer 22 so as to impact themicro-transverse motions vibrations or motions experienced by theultrasound transmission member 30 at this location where transversemotion is the greatest. In addition, the length of the combinedplurality of O-rings 330 extends across a larger proximal area of theultrasound transmission member 30 (when compared to the length of theabsorbers 224, 224 b), so that the embodiment of FIG. 8 is better suitedfor use in applications where the transverse motions are greater. Incontrast, the embodiments in FIGS. 5 and 7 may be better suited for usein applications where the transverse motions are lesser.

FIG. 9 illustrates a modification that can be made to the knob housing302 c in FIG. 8. In the knob housing 302 c in FIG. 9, the O-rings 330are replaced by a single absorber member 332 retained inside the bore300 c and around the ultrasound transmission member 30. The absorbermember 332 can have the same features, characteristics and materials asthe intermediate members 224 and 224 b described above. The length ofthe absorber member 332 can be provided such the absorber member 332covers the distance from the distal end 334 of the absorber member 332to the sonic connector 200, which is about one-quarter wavelength. Theembodiment in FIG. 9 shares the same benefits as the embodiment in FIG.8.

FIG. 10 illustrates another modification that can be made to the knobhousings 302 c in FIGS. 8 and 9. In particular, a combination of O-rings330 d and absorber members 332 d can be retained inside the bore 300 cand around the ultrasound transmission member 30. In FIG. 10, a group ofO-rings 330 d can be positioned between two separate absorber members332 d, although different arrangements of O-rings 330 d and absorbermembers 332 d can be utilized as well. The O-rings 330 d and absorbermembers 332 d can be the same as the O-rings 330 and absorber member 332described above. Again, the embodiment in FIG. 10 shares the samebenefits as the embodiments in FIGS. 8 and 9.

FIG. 11 illustrates modifications that can be made to the knob housing302 in FIG. 5, borrowing on the principles illustrated in FIGS. 8-10.The knob housing 302 in FIG. 11 is identical to the knob housing 302 inFIG. 5, so the same numerals are used to designate the same elements ofthe knob housing 302 in FIGS. 5 and 11. In FIG. 11, a first plurality ofO-rings 330 e can be retained inside the bore 300 and around theultrasound transmission member 30, and a second plurality of O-rings 330f can be retained inside the enlarged bore 322 and around the ultrasoundtransmission member 30. In addition, an intermediate member 224 e can beretained inside the bore 338 of the Y-connector 320 (at the connectionlocation between the enlarged bore 322 and the proximal end of theY-connector 320) and around the ultrasound transmission member 30. TheO-rings 330 e, 330 f and intermediate member 224 e can be the same asthe O-rings 330 and intermediate member 224 described above. Thedistance from the intermediate member 224 e to the sonic connector 200can be about one-quarter wavelength.

The provision of the sonic connectors and knob housings illustrated inFIGS. 5 and 7-11 are so effective in reducing stresses on the ultrasoundtransmission member 30 that they facilitate the use of a deflectabledistal end 16 x as described hereinabove. Previously-known ultrasoundcatheters have not been able to enjoy the luxury of a deflectable distalend because any bending at the distal end of the ultrasound transmissionmember 30 would cause the ultrasound transmission member 30 to bend too,thereby adding to the stresses already experienced by the ultrasoundtransmission member 30, resisting longitudinal propagation of ultrasoundenergy, and creating an additional source of heat, all of which wouldincrease the potential of breakage of the ultrasound transmission member30. Thus, the implementation of the sonic connectors illustrated inFIGS. 5 and 7-11 allows for the distal end of the ultrasoundtransmission member 30 to be bent without experiencing many of thesedrawbacks.

The present invention further provides for reverse irrigation to removeparticles that have been ablated during the ultrasound procedure.Referring to FIG. 2, irrigation fluid can be injected through a guidingcatheter 240 (and along the outer surface of the catheter body 12) asshown by the arrows 242. The irrigation fluid will travel to the distalhead 34 of the catheter 10, and will carry the particles through thechannel 74 in a reverse direction (i.e., from distal to proximal) andthrough the lumen 18. The irrigation fluid and particles will travel ina proximal direction along the lumen 18 to the infusion tube 70, and iscollected into a bottle or container 69 that can be connected to theinfusion tube 70. During this operation, the injection pump 68 can serveas a negative pressure pump.

As yet a further alternative, particles can be removed by applying avacuum to remove the particles via the lumen of the guidewire tube 80.For example, in an “over-the-wire” catheter embodiment, particles can beremoved via the lumen of the guidewire tube 80 using a pump or asyringe.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention.

1. An ultrasound catheter comprising: an elongate flexible catheter bodyhaving a proximal end, a distal end and at least one lumen extendinglongitudinally therethrough; an ultrasound transmission member extendinglongitudinally through the lumen of the catheter body, the ultrasoundtransmission member having a proximal end and a distal end positioned atthe distal end of the catheter body; a sonic connector positioned on theproximal end of the ultrasound transmission member for connecting theultrasound transmission member to a separate ultrasound generatingdevice, the sonic connector comprising a proximal section for connectionto a separate ultrasound generating device, and a front portionextending distally from the central portion, the front portion having abore which receives the proximal end of the ultrasound transmissionmember; and a tubular member separate and spaced-apart from the frontportion of the sonic connector by a distance of about one-quarterwavelength, the tubular member having a bore that receives a portion ofthe ultrasound transmission member; wherein the front portion and theultrasound transmission member are coupled together, and the tubularmember and the ultrasound transmission member are coupled together. 2.The catheter of claim 1, further including means positioned between theultrasound transmission member and a portion of the bore of the tubularmember for absorbing transverse motions of the ultrasound transmissionmember.
 3. The catheter of claim 1, wherein the sonic connector furtherincludes a central portion extending proximally from the front portion,with the central portion coupling the sonic connector to a housing. 4.The catheter of claim 1, wherein the front portion and the ultrasoundtransmission member are crimped together, and the tubular member and theultrasound transmission member are crimped together.